In which proxy war during the Cold War was containment successful?

Containment was considered successful during the Korean War (1950-1953). The United States and its allies intervened to prevent the spread of communism from North Korea into South Korea, leading to a stalemate that ultimately established a demilitarized zone and preserved South Korea as a non-communist state. This marked a significant achievement for U.S. containment policy, as it effectively limited communist expansion in East Asia, despite the ongoing tensions that followed.